When isolating one production zone from another, one of the challenges is that the borehole wall is not smooth and even. Therefore, several attempts have been made to provide annular barriers capable of providing proper sealing towards such uneven surfaces.
One way of providing zone isolation is to use annular barriers comprising expandable sleeves arranged on the outside of the well tubular structure. Once expanded, the sleeve abuts the inner surface of the borehole wall in order to provide the zone isolation. Sealing means are arranged on the outside of the sleeve for abutting the wall of the borehole and improving the sealing ability of the annular barrier. However, the sealing means do not always provide sufficient sealing, but the sealing means cannot be enlarged since they will then also enlarge the outer diameter of the annular barrier, and as the annular barrier is submerged down the borehole, such enlarged sealing means will bump into the borehole wall and thus be damaged.